Compiling pingus 0.6.0 fails

[Sebastian Erler]

Hello,

I tried to compile pingus 0.6.0 
and got the following errors:

generic_property_frame.cxx: In member function `void
   EditorNS::GenericPropertyFrame::begin_add_enum_box(const std::string&, int*)
   ':
generic_property_frame.cxx:272: error: `assert' undeclared (first use this
   function)
generic_property_frame.cxx:272: error: (Each undeclared identifier is reported
   only once for each function it appears in.)
generic_property_frame.cxx: In member function `void
   EditorNS::GenericPropertyFrame::add_enum_value(const std::string&, int)':
generic_property_frame.cxx:279: error: `assert' undeclared (first use this
   function)
generic_property_frame.cxx: In member function `void
   EditorNS::GenericPropertyFrame::end_add_enum_box()':
generic_property_frame.cxx:286: error: `assert' undeclared (first use this
   function)
make[3]: *** [generic_property_frame.o] Fehler 1
make[3]: Leaving directory `/home/user/pingus-0.6.0/src/editor'
make[2]: *** [all-recursive] Fehler 1
make[2]: Leaving directory `/home/user/pingus-0.6.0/src'
make[1]: *** [all-recursive] Fehler 1
make[1]: Leaving directory `/home/user/pingus-0.6.0'
make: *** [all] Fehler 2

What can I do to get it compiled?

Sebastian